A turbofan gas turbine engine may be used to power aircraft and may include, for example, a fan section, a compressor section, a combustion section, a turbine section, and an exhaust section, where each section has components that are mounted to a rotor. The fan section induces air from the surrounding environment into the engine and accelerates a fraction of the air toward the compressor section. The remaining fraction of air is accelerated into and through a bypass plenum, and out the exhaust section.
The compressor section, which may include a high pressure compressor and a low pressure compressor, raises the pressure of the air it receives from the fan section to a relatively high level. The compressed air then enters the combustion section, where a ring of fuel nozzles injects a steady stream of fuel into a plenum. The injected fuel is ignited to produce high-energy, hot combusted air. The air then flows into and through the turbine section causing turbine blades on a rotating disk to rotate and generate energy. This energy is used to power the fan and compressor sections. The air exiting the turbine section is exhausted from the engine via the exhaust section, and the energy remaining in the exhaust air aids the thrust generated by the air flowing through the bypass plenum.
During operation, the turbine blades, the rotating disk, and other components of the turbine section may be exposed to the hot combusted air. To prevent the turbine section components from overheating, a cooling system may be included. In some engines, cooling air extracted from other parts of the engine, such as from the compressor section, may be bled at compressor-discharge conditions and directed to the turbine section components. To improve cooling effectiveness of the cooling air, a flow rate of the cooling air may be increased. However, because the extraction of cooling air does not contribute to providing power to the turbine for engine operation, providing an excessive quantity of cooling air flow may undesirably increase engine fuel consumption, which may, in turn, reduce the power output of the gas turbine engine. These issues may be exacerbated in the case of small gas turbine engines (e.g., turbine engines having turbine inlet corrected airflows that are less than 1 lbm/sec). In particular, gaps between rotating and non-rotating components of small gas turbine engines, as well as seals included in these engines, are generally designed to minimize clearances therebetween and to have minimum tolerances. Therefore, an amount of gas leakage within small gas turbine engines may not decrease, despite scale-down of engine dimensions.
Accordingly, it is desirable to provide an improved system for cooling the components of an engine turbine section, including an engine turbine section of a small gas turbine engine. In addition, it is desirable for the improved system to cool engine components with minimal effect on engine fuel consumption. Moreover, it is desirable for the improved system to be relatively simple to implement. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.